It has recently been proposed to use amorphous materials having high permeability and less iron loss in cores for heightening efficiency of motors and saving energy.
A core employing the amorphous material is, as seen in Japanese Patent Publication Hei-5-109545/(1993), alternately laminated with oriented silicon steel sheets and the amorphous materials, with a laminated core component mechanically connected by caulking.
Japanese Patent Publication Hei-9-215279/(1997) discloses use of projections and through-holes as a caulking means for a laminated core.
Since the composing material, especially, the amorphous material, has high brittleness and it itself is very thin, the production does not depend on punching out one sheet at a time but depends on steps of laminating the plural amorphous thin sheets unified in one component using adhesives, followed by integrally punching the caulking through-holes and caulking projections.
Thus, it has been adopted to use the caulking means as a final caulking.
However, in case the materials are once laminated and then punched out, since punching is done especially on a plurality of layered materials of high brittleness, it is difficult to stably form caulking projections through to the lower layers of the amorphous laminated sheets, as a result of which sufficient caulking strength is not effected.
In addition, the lamination formed core is weak in caulking strength and there is thus a problem of the core breaking.
Further, there is a problem that micro cores, as for pocket telephones, could not be produced from the amorphous thin sheet material.